Because the ability to buy individual cards is so helpful, you should only ever spend these when building a specific deck
For individual cards and older booster packs and boxes, you will just have to gain a lot of experience and learn the nuances of real Pokemon products and then make educated purchases, ideally with a means of recourse if it turns out you were scammed (some kind of buyer protection program, etc)
A card's color identity includes its colors (taking into account its color indicator if it has one), plus the colors of any colored mana symbols in its rules text
Toxic Mechanics and Interactions Toxic interacts with other mechanics in Magic in fascinating ways
Roaming Throne appears in more and more decks
There are multiple Lessons that let you search for additional lands, allowing you to accelerate toward massive payoffs